Steering mechanism for motor vehicles



Nov. 26, 1940. J, N, TNT 2,223,274

STEERING MECHANISM FOR MOTOR VEHICLES Filed Oct. 18, 1939 2 Sheets-Sheet J.

Inbentor 6 JOHN NoH- TAIT Attorney Nov. 26, 1940.

J. N. H.'TAlT STEERING MECHANISM FOR. MOTOR VEHICLES Filed Oct. 18. 1939 2 Sheets-Sheet 2 Inventor JOHN N- 11. TAIT A ttofney Patented Nov. 26, 1940 STEERING MECHANISM FOR MOTOR VEHICLES Jenn Noel Hutton Tait, C'oventrylEnglandas- Signor to The Birmingham Small Arms Company Limited, Birmingham, England, a British company Application October 18, 1939, Serial No. 300,078 In Great Britain October 17, 1938 10 Claims.

This invention relates to steering mechanism for motor vehicles of the kind wherein both the front and the rear wheels are adapted to be driven and steered, and is particularly suitable for use with a steering mechanism such as is described and claimed in application Serial No. 313,484, filed January 12, 1940, in which progressive steering of the front andrear Wheels is effected by, means of a grooved master or guide plate operating in conjunction with a laterally displaceable rocking lever, the ends of which are respectively connectedby lever and link mechanism to the front and the rear steering wheels.

The object of the present invention is to provide, an improved construction and arrangement of lever and link mechanism adapted to provide a maximum groundclearance, a minimum friction lossin operation, a minimum toe-in variation with road wheel vertical movement when steering in straight direction, and also to steer the wheels with suitable fAckerman effect. According to the invention. there is provided a steering mechanism for motor vehicles of the kind, referred to whereinone end of the rocking lever controlledby the steering gear is adapted by 'means of suitably disposed linkages to rotate a lever to which are pivotally connected two oppositely disposed sets of linkages associated respectively with the two front wheels insuch a 30 way that rotation of thesaid lever by movement of the rocking lever effects steering of the front wheels. a

According 'to thepreferred arrangement the other end of the rocking lever is adapted by 3 means of suitably disposed linkages torotate a further lever to which are pivotally connected two oppositely disposed sets of linkages associated respectively with the two rear wheels in such a way that rotation of the said further lever by movement of the rocking lever effects steeringof the rear wheels.

These and other features of the invention will be more completely understood from the following detailed description which is given in conjunction with the accompanying' drawings, in which-- Figure 1 is aplan' View in skeleton form of a motor, vehicle embodying a steering mechanism constructed in accordance with the invention, only those parts of the vehicle being shown which are essential for a complete understanding of the invention, while r Figure 2 is also a plan View in skeleton form of a motor vehicle embodying the invention and illustrates a modification of the arrangement shown in Figure 1.

Referring now to Figure 1 of these drawings, the side arms It of the ,chassisof the vehicle are shown in dotted lines, these side arms being 5 provided with three transverse frame members 5, 5a and iib which are adapted to support the Various shafts of the linkage mechanisms to be described.

The steering gear 34 is pivotally connected by means of a link to the centre partof an endwise displaceable rocking lever I, this rocking lever being mounted in a'fixed guide plate 38 of the kind described in the aforesaid application. One end of this rocking lever i is connected by means of a link 2 to a laterally disposed horizontal lever 3 keyed on to a-vertically disposed shaft l mounted in suitable bearings carried on the chassis frame. 5, and to the :said vertical shaft 4 is keyed a lever posed pivot pins 1 and 8 which are respectively connected by links 9 and ill toonearm of bell crank levers i2 and i3 mounted or pivoted on the chassis frame 5 towards the near and off sides thereof, the other arms i l and italof said bell crank levers i2 and i3 being arranged to pass through longitudinal slots formed in the side members N5. of the chassis frame in order to provide good ground clearance, and to the said out- Wardly projecting arms M and Ma of said'bell 30 crank levers l2 and iii are connected laterally '1 disposed levers ii and Ila. keyed to the wheel swivels l8 and Ida of the frontwheels 56 by means'of-links l9 and lira which are substantially horizontal when the chassis frame of the vehicle is at a normal height above level ground.

The aforesaid levers and links are so disposed and arranged as to provide the desired Ackerman effect, that is to say, inturning a corner, the inner wheel'is turned through a greater angle than the outer wheel. V

The mechanism for steering the rear wheels comprises a link 28 connecting the other or opposite end of the aforesaid rocking lever to a centrally pivoted bell crank lever 2i disposed in a horizontal plane the other end of said bell crank lever 2| being linked to a lever 22 keyed to a centrallydisposed vertical shaft 23, and to 'the"latter is keyed a lever Z i' carrying two laterally disposed pivot pins 25 and 25 which are respectively connected by links '27, 23, levers 29, 30, links 31, SIA, levers 32, 32A to the swivels 33, 33A ofthe rear wheels 31 to effect steering of same ina manner similar to thatalready de- 6 carrying two laterally dis- 20 scribed. for effecting the steering of the front wheels.

The operation of the rocking lever I, which is described in detail in the aforesaid application, may be briefly described for the purposes of the present invention as follows: Assuming the parts to be as shown in Fig. 1, operation of the steeringgear 34 to steer the vehicle to the right or left will reciprocate the link 35 and thereby rock the lever I about the pivot pin 39 'to which the link 20 is connected, and which normally engages in a recess 40 in the guide plate as a fulcrum, thereby reciprocating the link 2 which, in turn, rocks the levers 3 and 6 and, through the linkages 9 and. I9 and I 0 and Hill and bell cranks I2 and IS, steer the front wheels 36 through the'levers I l and H fixed to the swivels of these wheels. During this operation, the pivot pin 4| on the end of the rocking lever I to which the link 2 is attached swings in a slot 42 in the guide plate, and if it moves sufficiently far will engage in one or the other of the notches 43 and M at the ends of this slot, thereby locking the front wheels from further steering movement, and the resultant endwise movement of the rocking lever I withdrawing the pivot pin 39 from the notch 40 in the guide plate and thereby unlocking the rocking lever to efiect steering by the rear wheels. Further operation of the steering gear in the. same direction as before will cause the lever I to rock about the pivot pin 4| as a center, thereby reciprocating the link 20 and, through the levers 2i, 22 and 24, linkages 21, 28, 3i and 3%, bell cranks 29 and 30 and levers 32 and 32 fixed to the swivels of the rear wheels '31, will efiect steering of the rear wheels to further steer the vehicle in the same direction in which the front wheels are steering it. By moving the rocking lever I endwise from the position shown in Fig. 1 so thatits pivot pin 39 is withbell crank lever 2I, as used in the arrangement of Figure 1 is omitted, a link 2011 which is pivoted to the end of the rocking lever I, beingv directly pivoted to the end of the lever 22 which is keyed to the vertical shaft 23, so that this shaft is directly rotated by movement of the link Zlla. All other parts of the steering mechanism are identical with those already described in conjunction with Figure 1.

It is to be understood however that the invention is not to be regarded as limited to the particular details of construction described and illustrated, for example, in a modified form of construction, the levers 3 and 6, and the levers 22 and 24 instead of being separately keyed to the shafts 4 and 23, might be formed as bell-crank levers mounted on the shafts 4 and 23 respectively. This modified form of construction could be equally well applied to either of the arrangements shown in Figures 1 and 2 of the drawings.

In the application of steering mechanism constructed in accordance with this invention, for use in conjunction with independent Wheel suspension of the kind comprising laterally disposed upper and lower spring supported links, it is found necessary, in order to provide a clearance for the levers keyed to the lower end of the wheel swivels,

and at the same time to provide maximum ground clearance, to arch in an upward direction the lower of the aforesaid links.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Steering mechanism for motor vehicles of the type steered at least by its front wheels, comprising a steering gear, an endwise displaceable rocking lever having means pivotally connecting it between its ends to the steering gear for reciprocation thereby, two oppositely disposed linkages associated respectively With the two front wheels of the vehicle, means including a second lever connecting said linkages to one end of said rocking lever and a guide plate engageable, by endwise displacement of said rocking lever, with the other end of said rocking lever as a fulcrum about which said rocking lever, when reciprocated, is rockable as a center, said second lever being rotatable by reciprocation of said rocking lever to eifect steering of the front wheels.

2. Steering mechanism for motor vehicles of the type steered at least by two of its wheels at one end, comprising a steering gear, a rocking lever having means connecting it to said steering gear to be controlled thereby, two oppositely disposed linkages associated respectively with said two wheels of the vehicle, means including a second lever connecting said linkages to one end of said rocking lever, said second lever bein'g'rotatable by movement of said rocking lever and carrying a. pair of pivot pins, and said linkages of each of which is linked the respective pivot pin, and a pair of levers linked respectively to the other arms of said bell crank levers and fixed to the wheel swivels of said two wheels of the vehicle to effect steering thereof.

3. Steering mechanism for motor vehicles of the type steered at least by two of its Wheels at one end, comprising a steering gear, a rocking lever having means connecting it to said steering gear to be controlledthereby, two oppositely disposed linkages associated respectively with said two wheels of the vehicle, means including a second lever connecting said linkages to one end of said rocking lever, said second lever being rotatable by movement of said rocking lever and carrying a pair of pivot pins, and said linkages comprising a pair of bell crank levers to one arm of each of which is linked the respective'pivot pin, and a pair of levers linked respectively'to the other arms of said bell crank levers and fixed to the wheel swivels ofsaid two wheels of the vehicle to effect steering thereof, said bell crank levers being arranged to pass through longitudinal slots formed in the chassis frame of the vehicle. 7 r

4. Steering mechanism for motor vehicles. of the type steered by its front and rear wheels, comprising a steering gear, an endwise displaceable rocking lever means pivotally connecting said lever between its ends to the steering gear for reciprocation thereby, two oppositely disposed linkages associated respectively with the two front wheels of the vehicle, means including a second lever connecting said linkages to one end of said rocking lever, a guide plate engageable, by endwise displacement of said rocking lever, with one or the other end of said rocking lever as a fulcrum about which said rocking lever, when reciprocated, is rockable as a center, said second lever being rotatable by reciprocation of said a, further lever, means connecting said further further lever and associated respectively with the two rear wheels of the motor vehicle, said further lever being rotatable by reciprocation of said rocking lever to efiect steering of the rear wheels.

5. Steering mechanism according to, claim 4, wherein said further lever carries a pair of pivot 'pins which are linked respectively to one arm of a pair of bell crank levers the other arms of which are linked respectively to a pair of levers fixed to the wheel swivels of the two rear wheels of the vehicle.

6. Steering mechanism according to claim 4, wherein said further lever carries a pair of pivot pins which are linked respectively to one arm of a pair of bell crank levers the other arms of which are linked respectively to a pair of levers fixed to the wheel swivels of the two rear wheels of the vehicle, said bell crank levers being arranged to pass through longitudinal slots formed in the chassis frame of the vehicle.

7. Steering mechanism according to claim 4,

wherein said further lever is fixed to a shaft, and said means connecting said further lever to said rocking lever'includes an actuating lever one end of which is fixed to said shaft and the other end of which is pivotally connected to said rocking lever by a linkage comprising a link pivotally interconnected between said other end of said rocking lever and said other 'end of said actuating lever.

8. Steering mechanism according to. claim 4,

wherein said further lever comprises an arm of a bell crank lever, said arm being pivotally connected to said oppositely disposed linkages associated with the two rear wheels of the vehicle, and said means connecting said further lever to said rocking lever includes the other arm of said bell crank lever which is pivotally connected to the said rocking lever by a linkage comprising a link pivotally interconnected between said other end of said rocking lever and said other arm ofsaid bell crank lever.

' 9. Steering mechanism according to claim 4, wherein said further lever is fixed to a shaft, and said means connecting said further lever to said rocking lever includes anactuating lever one end of whichis fixed to said shaft, the other end of said actuating lever being pivotally connected to the end of said rocking lever by alinkage comprising a link connected to one end of a bell crank lever the other end of which is pivotally connected by a further link to the end of said actuating lever.

10. Steering mechanism according to claim 4, wherein said further lever comprises an arm of a bell crank lever, said arm being pivotally connected to said oppositely disposed linkages assoiated with the two rear wheels of the vehicle,

and said means connecting said. further lever to said rocking lever includes the other arm of said bell crank lever which is pivotally connected to said other end of said rocking lever by a link pivotally connected toone end of a lever the other end of which is pivotally connected by a further link to the end of said rocking lever.

J OHN NOEL HUTTON TAIT. 

